Merge pull request #900 from RobAltena/master

add serialization example.

Author: AlexDBlack

nd4j-examples/src/main/java/org/nd4j/examples/Nd4jEx16_Serialization.java

@@ -0,0 +1,76 @@
+package org.nd4j.examples;
+
+import org.nd4j.linalg.api.ndarray.INDArray;
+import org.nd4j.linalg.factory.Nd4j;
+
+import java.io.*;
+import java.util.Map;
+import java.util.Objects;
+
+/**
+ * Nd4j provides serialization of INDArrays many formats. This example gives some examples for binary and text
+ * serialization.
+ */
+public class Nd4jEx16_Serialization {
+
+    public static void main(String[] args) throws Exception {
+        ClassLoader loader = Nd4jEx16_Serialization.class.getClassLoader();  // used to read files from resources.
+
+        // 1. binary format from stream.
+        INDArray arrWrite = Nd4j.linspace(1,25,25).reshape(5,5);
+        String pathname = "tmp.bin";
+
+        try(DataOutputStream sWrite = new DataOutputStream(new FileOutputStream(new File(pathname )))){
+            Nd4j.write(arrWrite, sWrite);
+        }
+
+        INDArray arrRead;
+        try(DataInputStream sRead = new DataInputStream(new FileInputStream(new File(pathname )))){
+            arrRead = Nd4j.read(sRead);
+        }
+
+        // We now have our test matrix in arrRead
+        System.out.println("Read from binary stream:" );
+        System.out.println(arrRead );
+
+
+        // 2. Write and read the numpy npy format:
+        File file =  new File("nd4j.npy" );
+        Nd4j.writeAsNumpy(arrRead, file ); // Try to read this file from Python:   y = np.load('nd4j.npy')
+
+        arrRead = Nd4j.createFromNpyFile(file); // We can read these files from nd4j.
+        System.out.println();
+        System.out.println("Read from Numpy .npy format:" );
+        System.out.println(arrRead);
+
+
+        // 3. Read the numpy npz format:
+        file =  new File( Objects.requireNonNull(loader.getResource("numpyz.npz")).getFile());
+
+        Map<String, INDArray> arrayMap = Nd4j.createFromNpzFile(file); //We get a map reading an .npz file.
+        System.out.println();
+        System.out.println("Read from Numpy .npz format:" );
+        System.out.println(arrayMap.get("arr_0")); //We know there are 2 arrays in the .npz file.
+        System.out.println(arrayMap.get("arr_1"));
+
+
+        // 4. binary format from file.
+        file =  new File(pathname);
+        Nd4j.saveBinary(arrWrite, file);
+        arrRead = Nd4j.readBinary(file );
+        System.out.println();
+        System.out.println("Read from binary format:" );
+        System.out.println(arrRead);
+
+
+        // 5. read a csv file.
+        file =  new File( Objects.requireNonNull(loader.getResource("twentyfive.csv")).getFile());
+        String Filename = file.getAbsolutePath();
+        arrRead  = Nd4j.readNumpy(Filename, ",");
+        System.out.println();
+        System.out.println("Read from csv format:" );
+        System.out.println(arrRead);
+
+    }
+
+}

nd4j-examples/src/main/resources/numpyz.npz

@@ -0,0 +1,5 @@
+1.000000000000000000e+00,2.000000000000000000e+00,3.000000000000000000e+00,4.000000000000000000e+00,5.000000000000000000e+00
+6.000000000000000000e+00,7.000000000000000000e+00,8.000000000000000000e+00,9.000000000000000000e+00,1.000000000000000000e+01
+1.100000000000000000e+01,1.200000000000000000e+01,1.300000000000000000e+01,1.400000000000000000e+01,1.500000000000000000e+01
+1.600000000000000000e+01,1.700000000000000000e+01,1.800000000000000000e+01,1.900000000000000000e+01,2.000000000000000000e+01
+2.100000000000000000e+01,2.200000000000000000e+01,2.300000000000000000e+01,2.400000000000000000e+01,2.500000000000000000e+01